我正在努力使我的主要活动开启另一项活动（ListAtivity）。但是，当我点击按钮应用程序崩溃并出现以下异常时：
01-26 17:12:58.341: E/AndroidRuntime(790): FATAL EXCEPTION: main
01-26 17:12:58.341: E/AndroidRuntime(790): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.slideoutmenu/com.example.slideoutmenu.ListViewActivity}: android.os.NetworkOnMainThreadException
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.os.Handler.dispatchMessage(Handler.java:99)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.os.Looper.loop(Looper.java:137)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread.main(ActivityThread.java:5039)
01-26 17:12:58.341: E/AndroidRuntime(790): at java.lang.reflect.Method.invokeNative(Native Method)
01-26 17:12:58.341: E/AndroidRuntime(790): at java.lang.reflect.Method.invoke(Method.java:511)
01-26 17:12:58.341: E/AndroidRuntime(790): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-26 17:12:58.341: E/AndroidRuntime(790): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-26 17:12:58.341: E/AndroidRuntime(790): at dalvik.system.NativeStart.main(Native Method)
01-26 17:12:58.341: E/AndroidRuntime(790): Caused by: android.os.NetworkOnMainThreadException
01-26 17:12:58.341: E/AndroidRuntime(790): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
01-26 17:12:58.341: E/AndroidRuntime(790): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-26 17:12:58.341: E/AndroidRuntime(790): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-26 17:12:58.341: E/AndroidRuntime(790): at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-26 17:12:58.341: E/AndroidRuntime(790): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
01-26 17:12:58.341: E/AndroidRuntime(790): at com.example.slideoutmenu.JSONParser.getJSONFromUrl(JSONParser.java:34)
01-26 17:12:58.341: E/AndroidRuntime(790): at com.example.slideoutmenu.ListViewActivity.onCreate(ListViewActivity.java:57)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.Activity.performCreate(Activity.java:5104)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-26 17:12:58.341: E/AndroidRuntime(790): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
以下是主要活动：
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class LayerStack extends Activity {
//Declare
private LinearLayout slidingPanel;
private boolean isExpanded;
private DisplayMetrics metrics;
private WebView webView;
private RelativeLayout headerPanel;
private RelativeLayout menuPanel;
private int panelWidth;
private ImageView menuViewButton;
private Button button;
private TextView menubutton1;
FrameLayout.LayoutParams menuPanelParameters;
FrameLayout.LayoutParams slidingPanelParameters;
LinearLayout.LayoutParams headerPanelParameters ;
LinearLayout.LayoutParams listViewParameters;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_layer_stack);
//Initialize
metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
panelWidth = (int) ((metrics.widthPixels)*0.75);
headerPanel = (RelativeLayout) findViewById(R.id.header);
headerPanelParameters = (LinearLayout.LayoutParams) headerPanel.getLayoutParams();
headerPanelParameters.width = metrics.widthPixels;
headerPanel.setLayoutParams(headerPanelParameters);
menuPanel = (RelativeLayout) findViewById(R.id.menuPanel);
menuPanelParameters = (FrameLayout.LayoutParams) menuPanel.getLayoutParams();
menuPanelParameters.width = panelWidth;
menuPanel.setLayoutParams(menuPanelParameters);
slidingPanel = (LinearLayout) findViewById(R.id.slidingPanel);
slidingPanelParameters = (FrameLayout.LayoutParams) slidingPanel.getLayoutParams();
slidingPanelParameters.width = metrics.widthPixels;
slidingPanel.setLayoutParams(slidingPanelParameters);
menubutton1 = (TextView) findViewById(R.id.menu_item_1);
menubutton1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent i = new Intent(getApplicationContext(), ListViewActivity.class);
startActivity(i);
}
});
webView = (WebView) findViewById(R.id.webView1);
webView.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url){
view.loadUrl(url);
return true;
}
});
webView.loadUrl("http://www.google.com.br");
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent i = new Intent(getApplicationContext(), ListViewActivity.class);
startActivity(i);
}
});
//Slide the Panel
menuViewButton = (ImageView) findViewById(R.id.menuViewButton);
menuViewButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if(!isExpanded){
isExpanded = true;
//Expand
new ExpandAnimation(slidingPanel, panelWidth,
Animation.RELATIVE_TO_SELF, 0.0f,
Animation.RELATIVE_TO_SELF, 0.75f, 0, 0.0f, 0, 0.0f);
}else{
isExpanded = false;
//Collapse
new CollapseAnimation(slidingPanel,panelWidth,
TranslateAnimation.RELATIVE_TO_SELF, 0.75f,
TranslateAnimation.RELATIVE_TO_SELF, 0.0f, 0, 0.0f, 0, 0.0f);
}
}
});
}
}
这里是我要打开的列表视图
package com.example.slideoutmenu;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ListViewActivity extends ListActivity {
// url to make request
private static String url = "http://api.androidhive.info/contacts/";
// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
private static final String TAG_ADDRESS = "address";
private static final String TAG_GENDER = "gender";
private static final String TAG_PHONE = "phone";
private static final String TAG_PHONE_MOBILE = "mobile";
private static final String TAG_PHONE_HOME = "home";
private static final String TAG_PHONE_OFFICE = "office";
JSONArray contacts = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_layer_2);
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
JSONParser jParser = new JSONParser();
JSONObject json = jParser.getJSONFromUrl(url);
try {
contacts = json.getJSONArray(TAG_CONTACTS);
for(int i = 0; i < contacts.length(); i++){
JSONObject c = contacts.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
String address = c.getString(TAG_ADDRESS);
String gender = c.getString(TAG_GENDER);
JSONObject phone = c.getJSONObject(TAG_PHONE);
String mobile = phone.getString(TAG_PHONE_MOBILE);
String home = phone.getString(TAG_PHONE_HOME);
String office = phone.getString(TAG_PHONE_OFFICE);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_ID, id);
map.put(TAG_NAME, name);
map.put(TAG_EMAIL, email);
map.put(TAG_PHONE_MOBILE, mobile);
contactList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
ListAdapter adapter = new SimpleAdapter(this, contactList,
R.layout.list_item,
new String[] { TAG_NAME, TAG_EMAIL, TAG_PHONE_MOBILE }, new int[] {
R.id.name, R.id.email, R.id.mobile });
setListAdapter(adapter);
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
String cost = ((TextView) view.findViewById(R.id.email)).getText().toString();
String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString();
Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_EMAIL, cost);
in.putExtra(TAG_PHONE_MOBILE, description);
startActivity(in);
}
});
}
}
答案 0 :(得分：13)
Caused by: android.os.NetworkOnMainThreadException
You cannot perform network operations on the main Thread（参见NetworkOnMainThreadException）。您需要将获取JSON对象的代码移动到另一个Thread，可能使用AsyncTask。